So I finally got my trans temp gauge installed in my 07 Taco...
Why: IMO an auto tranny isn't the best tranny for backroads towing, there just isn't enough pump or airflow to keep them cool. This is bad for two reasons one the trans can be cooked and two it can cause the engine to overheat as the trans is putting 200*+ fluid into a radiator when the engine is only putting 190-200* so the trans fluid can actually cause the engine coolant not to cool (I have seen it happen more than once). But IMO the 5 spd auto in the taco is a better option, plus this isnt a HD tow rig, just a LD one. So I figured a gauge to keep an eye on the temps was the best option, plus it would tell me if the OEM aux cooler with the tow package was enough.
Where: So I started doing some research on where people with trans temp gauges mount them. I found the most common was in the pan. Most ford/chevy trannnies have a test port in the pan and they put the gauge there. Well the toyota doesnt have this, and I found its not the hottest place, which is what I wanted to see. So I found that some Dodge guys tap them into the line going from the trans to the cooler. I also found some toyota guys doing this but not until it goes to the rubber line, about 3' in front of the tranny, IMO way to far away for an accurate reading. So in the hardline it was.
How: So I ordered a spare cooler outlet hardline from toyota. I also ordered a ISSPRO trans temp gauge. When they both were here I went to the local hydraulic supply shop and said I want this in here. Turns out the hardline is a 10mm hardline. So two 10mm compression fittings, a brass tee and a 1/4" to 1/8" reducing bushing later and I had my setup. I came home and put the "T" together and went out to the truck. I held it to the hardline to find the closest spot I could attach it to the tranny. With that spot noted I cut the appropriate section of the replacement line out and was ready for an install. For the sender install I disconnected the trans lines at the cooler and tried to blow the fluid back into the tranny but there must be a check valve, so I made a small mess. But it went in very easily. Two clamps on the engine and the one fitting on the tranny, the fwd end is a hose and hose clamp. About 30 minutes later it was installed. I waited until it was in to tighten the compression fittings so that I could get the angle perfect. I then started running the sender line. The ISSPRO setup comes with a sender, amplifier, and gauge. I also got a extension for the gauge between the amp and gauge. I put the sender wires inside a piece of 1/4" fuel line and ran it thru the crossmember under the aft of the engine. I ran it up thru the engine bay to a grommet in the firewall. My oil psi sender wire also runs thry this grommet. The wire then plugs into the amplifier and thats mounted on the fire wall. The gauge itself is mounted on the dash below the 4wd shift knob. I originally wanted a a-pillar mount but one of those wont be made due to the side airbag option, so I am told. So I got a universal pod from autometer, and screwed it to the dash. The wires run thru the dash in the coin tray (e-brake location on manuals) and are out of sight. I got power from a tap-a-fuse that is powered by the "on" position of the ignition. I still need to run a wire for backlighting and will tap into the trailer brake controller harness wire that is hot with parking lights and my brake controller doesn't use it.
Impressions: This was relatively an easy install, and works awesome. The gauge is easy to see when driving, and from the short time I have had it installed I would say VERY necessary. Around town driving empty I have seen temps as high as 190*, which isnt too bad, but wow. On the interstate I have seen 190* empty at 75mph and 210* towing 1800lbs at 75mph. All these readings are on 95-105* days. The couple mornings I have driven to work in the 50-60* range it doesnt get above 130* unless I am stopped in traffic. The temp jumps very fast when stuck in traffic. The hottest I have seen so far is 230*, this was on a 95* day at 7500 feet towing 1800lbs, 500lbs in the bed and climbing a slow switchback road at 10mph in 4lo. I dont really want to see temps above the 220-230* range, and would change my fluid if it ever got above 250*. So thats where it stands, I do expect MUCH cooler temps this winter, but my towing is all summer related to I will most likley add a aux cooler with a fan that kicks on at 160*. I also am very disappointed in the aux cooler. It sits directly behind the bumper so at low speeds it get very little to no airflow. I went for 2 test drives today, the first one I saw 150-160* around town, the second one I took the bumper off and saw 140* and was driving MUCH harder and the temp drops super quick w/out the bumper where w/ the bumper it takes a LONG time to drop if it even will. This tells me that airflow over the aux cooler is a HUGE problem. I also have read that the normal operating temp of this tranny is 122-176*, so as you can see normal driving in the summer puts is 15* above this on a regular basis, with the aux cooler. So those of you without the tow package really need to get another cooler, and those with need another cooler/gauge if you do any backroads towing.
I know that the SGII will be able to read trans temps very soon and I will do this flash also. I am guessing that the gauges will read different when driving. I took my truck to toyota after the sender install to have them check the fluid level as you need to check it at a specific temp and I was unsure of how mine read compared to theirs. What I found was that mine was within +2* of both of the OEM sensors, but this was sitting at idle for 15-20 minutes so there was no load, just a constant recirculation. I would guess under driving conditions the OEM ones will read cooler, maybe as much as 20-30*+ since they look to be in the pan which gets cooled fluid and my sender is in the hardline, getting precooled fluid. The OEM fluid is synthetic and under towing conditions is good for 60K, but I will probably flush it at 30K.
The "T" in the hardline
The Gauge
The sender installed
Sender wire thru the crossmember
Thru the firewall
Why: IMO an auto tranny isn't the best tranny for backroads towing, there just isn't enough pump or airflow to keep them cool. This is bad for two reasons one the trans can be cooked and two it can cause the engine to overheat as the trans is putting 200*+ fluid into a radiator when the engine is only putting 190-200* so the trans fluid can actually cause the engine coolant not to cool (I have seen it happen more than once). But IMO the 5 spd auto in the taco is a better option, plus this isnt a HD tow rig, just a LD one. So I figured a gauge to keep an eye on the temps was the best option, plus it would tell me if the OEM aux cooler with the tow package was enough.
Where: So I started doing some research on where people with trans temp gauges mount them. I found the most common was in the pan. Most ford/chevy trannnies have a test port in the pan and they put the gauge there. Well the toyota doesnt have this, and I found its not the hottest place, which is what I wanted to see. So I found that some Dodge guys tap them into the line going from the trans to the cooler. I also found some toyota guys doing this but not until it goes to the rubber line, about 3' in front of the tranny, IMO way to far away for an accurate reading. So in the hardline it was.
How: So I ordered a spare cooler outlet hardline from toyota. I also ordered a ISSPRO trans temp gauge. When they both were here I went to the local hydraulic supply shop and said I want this in here. Turns out the hardline is a 10mm hardline. So two 10mm compression fittings, a brass tee and a 1/4" to 1/8" reducing bushing later and I had my setup. I came home and put the "T" together and went out to the truck. I held it to the hardline to find the closest spot I could attach it to the tranny. With that spot noted I cut the appropriate section of the replacement line out and was ready for an install. For the sender install I disconnected the trans lines at the cooler and tried to blow the fluid back into the tranny but there must be a check valve, so I made a small mess. But it went in very easily. Two clamps on the engine and the one fitting on the tranny, the fwd end is a hose and hose clamp. About 30 minutes later it was installed. I waited until it was in to tighten the compression fittings so that I could get the angle perfect. I then started running the sender line. The ISSPRO setup comes with a sender, amplifier, and gauge. I also got a extension for the gauge between the amp and gauge. I put the sender wires inside a piece of 1/4" fuel line and ran it thru the crossmember under the aft of the engine. I ran it up thru the engine bay to a grommet in the firewall. My oil psi sender wire also runs thry this grommet. The wire then plugs into the amplifier and thats mounted on the fire wall. The gauge itself is mounted on the dash below the 4wd shift knob. I originally wanted a a-pillar mount but one of those wont be made due to the side airbag option, so I am told. So I got a universal pod from autometer, and screwed it to the dash. The wires run thru the dash in the coin tray (e-brake location on manuals) and are out of sight. I got power from a tap-a-fuse that is powered by the "on" position of the ignition. I still need to run a wire for backlighting and will tap into the trailer brake controller harness wire that is hot with parking lights and my brake controller doesn't use it.
Impressions: This was relatively an easy install, and works awesome. The gauge is easy to see when driving, and from the short time I have had it installed I would say VERY necessary. Around town driving empty I have seen temps as high as 190*, which isnt too bad, but wow. On the interstate I have seen 190* empty at 75mph and 210* towing 1800lbs at 75mph. All these readings are on 95-105* days. The couple mornings I have driven to work in the 50-60* range it doesnt get above 130* unless I am stopped in traffic. The temp jumps very fast when stuck in traffic. The hottest I have seen so far is 230*, this was on a 95* day at 7500 feet towing 1800lbs, 500lbs in the bed and climbing a slow switchback road at 10mph in 4lo. I dont really want to see temps above the 220-230* range, and would change my fluid if it ever got above 250*. So thats where it stands, I do expect MUCH cooler temps this winter, but my towing is all summer related to I will most likley add a aux cooler with a fan that kicks on at 160*. I also am very disappointed in the aux cooler. It sits directly behind the bumper so at low speeds it get very little to no airflow. I went for 2 test drives today, the first one I saw 150-160* around town, the second one I took the bumper off and saw 140* and was driving MUCH harder and the temp drops super quick w/out the bumper where w/ the bumper it takes a LONG time to drop if it even will. This tells me that airflow over the aux cooler is a HUGE problem. I also have read that the normal operating temp of this tranny is 122-176*, so as you can see normal driving in the summer puts is 15* above this on a regular basis, with the aux cooler. So those of you without the tow package really need to get another cooler, and those with need another cooler/gauge if you do any backroads towing.
I know that the SGII will be able to read trans temps very soon and I will do this flash also. I am guessing that the gauges will read different when driving. I took my truck to toyota after the sender install to have them check the fluid level as you need to check it at a specific temp and I was unsure of how mine read compared to theirs. What I found was that mine was within +2* of both of the OEM sensors, but this was sitting at idle for 15-20 minutes so there was no load, just a constant recirculation. I would guess under driving conditions the OEM ones will read cooler, maybe as much as 20-30*+ since they look to be in the pan which gets cooled fluid and my sender is in the hardline, getting precooled fluid. The OEM fluid is synthetic and under towing conditions is good for 60K, but I will probably flush it at 30K.
The "T" in the hardline
The Gauge
The sender installed
Sender wire thru the crossmember
Thru the firewall